The Triumph Dolomite Club - Discussion Forum

A question I have about the generation system of a positive earth 1300 Fwd, I wonder if someone can assist with please?
As part of a recommison, due to the constant bright illumination of the ignition warning light.
I've rebuilt with new bearings and bushes, the dynamo which by doing the usual test of linking up the two terminals and putting a voltmeter between the link and ground.
This produced a voltage of between 15-28 volts with a slight increase in revs.
Reconnected the vehicle cables and, started up, still the ignition light was on, so we swapped the voltage regulator.
Bingo the ignition light was extinguished, and testing at the battery we got a voltage range of 12.9 at idle upto a maximum of 15 volts, I trust this is right???
But looking at the dashboard there's a charge gauge, with What looks to me to be D at the top and C at the bottom,
When the engine revs are raised the gauge needle moves toward D, not C, returning to the centre when at idle.
Trusting that the D stands for discharge there is still an issue with the system, or my dynamo rebuild??

1300's are negative earth, if you've reversed the polarity, the ammeter indication will be reversed......

Well I've not knowingly reversed the polarity, the battery is still connected positive earth as original. An the new voltage regulator is connected as per the original too.
Looking at the below picture I trust all is correct, less the brush springs obviously.
Should there be a link wire between the left and right brushes, there wasn't originally.

I don't believe there is a link lead, and I repeat that the car should be negative earth!

Sorry missed that major point you made
Triumph1300 Doh!
An the Charge / discharge gauge is actually an ammeter.
So it should be Negative earth, like a modern vehicle, as built from the factory I take?
Any idea why it would be positive earth now, or any point in anyone making it that polarity ??
If someone has changed the polarity is there anything I need to do to convert it back, other than swap the leads?
Surely there's implications with starter motor, etc..

Starter motor etc, shouldn't be a problem, but you will need to reflash the dynamo to ensure correct charging polarity.

The reg box should be ok.

Has it a radio fitted?

Where are you based?

No there's no radio to worry about, the dynamo I can do, and a lot of the other connections should be easy to swap over.
I will need to dig the workshop manual out from the owner and see if there's a wiring diagram in it, then connect up as it's described.
The cars in Birmingham, but it's not my car.
There's some dodgy wiring in the form of an add on hazard warning light, powered up
from the brake light switch!
Although I have been told that it's original, and untouched since the late owners death, I'm definitely feeling like someone's been dabbling.
Thank you for your assistance.

After a long look round the triumphs garage and a look at the battery that was fitted originally when we first cracked open the bonnet. It seems it had a 038 battery replaced back in about 1990 by someone who just jammed on a more modern battery 063? , taking no notice of the difference in post polaritys, this is fairly obvious from the cracked terminals on the cable's.
A glance in the workshop manual confirms the polarity is negative earth, so we have aquired a 038 battery with refilling plugs and this will be fitted up as original.
We need to flash the dynamo I trust, though I doubt that was done, when the battery was fitted incorrectly 25 years ago. I take the starter motor is unaffected??